The ready availability of a variety of highly flavorful foods coupled with the relatively sedentary lifestyles of a portion of the population has resulted in an accumulation of calories in these people. Estimates indicate that currently as much as 40% of the U.S. population is overweight. J. J. Beereboom, CRC Critical Reviews in Food Science and Nutrition, 11(4), pps. 401-413, May 1979. Consequently, an increasing number of people are practicing some form of dieting and/or monitoring of caloric intake. This has led to the successful introductions and rapid growth of a variety of reduced calorie food products, such as cake mixes, beers, wines, candies and sodas.
Two of the most significant contributors to the population's caloric intake are sucrose (i.e., common table sugar) and high fructose corn syrup. In fact, a great deal of effort has been expended to develop a functional reduced calorie sugar substitute.
In 1985, the Calorie Control Council's brochure Sweet Choices described the ideal sweetener as having the following characteristics:
same or greater sweetness as sucrose PA1 colorless PA1 odorless PA1 readily soluble in water PA1 stable PA1 functionally similar to sucrose PA1 economically feasible PA1 contribute reduced or no calories to the diet PA1 non-toxic and non-promoting of dental caries PA1 combinations of bulk extenders and available artificial sweeteners PA1 modified sugars
The Council commented that up to that date a sweetener having all those characteristics did not exist.
Sugars are best known as sweeteners, however, their role as functional components in foods is equally important. Sugar influences many food properties in addition to flavor. It alters the degree of hydration of many substances, influences the viscosity of starch pastes, the firmness of gelatin and pectin gels, and the formation and strength of gluten strands. It controls the gelatinization temperature of starch and the gelation temperatures of gluten and egg proteins. It affects the rate of spoilage due to the growth of micro-organisms. In many cases, it alters the color and texture of fruit products. It increases the moisture-retaining ability of many foods. The size of sugar crystals influences markedly the textural characteristics of candies and frostings, and it enhances the body of beverages. (See Paul and Palmer, Food Theory and Applications, pg. 47 (1972)). The concentration of sugar in the food product regulates the properties. As a result, the volume fraction of sugar in foods is often very high. This is commonly referred to as sugar's bulking characteristic. One of the major problems in developing a reduced calorie sugar substitute is to provide this bulking characteristic.
Most artificial sweeteners in use today have a greater relative sweetness than sucrose; thus, relatively small quantities are required to deliver the desired sweetness. Such low volume sweeteners may be acceptable for certain applications (e.g., beverages), however, they do not provide sufficient bulk and functionality for use in solid and semi-solid foods like baked goods and frozen desserts. In fact, even high intensity sweetener-containing beverages have a detectable reduction in their body. Two avenues have been explored to overcome this bulking problem:
Presently-available sweeteners and sweetener/bulk extender combinations are not satisfactory due to their significant deviation from the important functional characteristics of sucrose (e.g., solubility and control of starch gelatinization), significant caloric values, and negative physiological effects.
Polydextrose, produced by Pfizer Corp., is a non-sweet, randomly bonded glucan containing small amounts of sorbitol and citric acid. It is presently the most widely used reduced calorie bulk extender in foods. As a sugar substitute it contributes 1 kcal/g, which is equivalent to about 25% of the caloric contribution of sucrose. Unfortunately, polydextrose has a low laxative threshold and has little control of starch gelatinization. See Food Technology, January 1986, "Special Report: Sweeteners and Product Development", pg. 129.
U.S. Pat. No. 2,876,105, Jucaitis and Biudzius, issued Mar. 3, 1959, discloses another class of carbohydrate polymers to be used as bulk extenders. Other bulk extenders include gum arabic and gum tragacanth. However, they are not desirable since they are not readily soluble, especially in cold liquids, and they have high relative viscosities and they have little control of starch gelatinization. See U.S. Pat. No. 3,704,138, LaVia, issued Nov. 28, 1972.
Arabinogalactan (Larch Gum) is a highly branched polymer of arabinose and galactose obtained from the Western Larch tree. Though it has FDA clearance for use in foods and has many suitable physical properties, such as good solubility in solutions having low viscosities, actual use has been small due to taste, functional, heat-stability problems and poor starch gelatinization control.
U.S. Pat. No. 4,207,413, Szarek et al., issued June 10, 1980, discloses that L-sucrose (.alpha.-L-glucopyranosyl-.beta.-L-fructofuranoside) has identical sweetness to sucrose but is not metabolized on ingestion and is, therefore, non-caloric. The high cost of synthesizing this compound acts as a significant barrier to its development as a dietary sweetening agent. See Kirk-Othmer, Encyclopedia of Chemical Technology, third ed., Vol. 21, pg. 939 (1978). A later patent discloses that L-monosaccharides are also edible and non-caloric (U.S. Pat. No. 4,262,032, Levin, issued Apr. 14, 1981). These L-sugars are also very costly to synthesize.
Sugar alcohols, called alditols, have also been proposed as sugar substitutes. However, only a few alditols have been approved as food additives and they have limited dietary applications due to their low laxative threshold and significant caloric value. (See, Rothschild, Food Chemical News Guide, mannitol, pg. 255 (1987); sorbitol, pg. 430 (1982); xylitol, pg. 495 (1986)).
In order to test structure-sweetness correlations, Witczak and Whistler, Carbohydrate Research, 169 (1987), 252-257, synthesized a large group of compounds including the branched chain alditol, 2-C-(hydroxymethyl)-D-mannitol. Witczak and Whistler did not comment on the metabolizability of the compound.
U.S. Pat. No. 4,459,316, Bakal, issued July 10, 1984, teaches that di- and trisaccharides containing one levohexose component and at least one dextrohexose component (e.g., .alpha.-L-glucopyranosyl-D-fructofuranose) are non-caloric. These disaccharides are costly to synthesize due to the fact that they are prepared from a racemic mixture of D-hexoses and expensive L-hexoses.
Thus, a sugar replacement which is low in calories, inexpensive to synthesize, sweet, functional (especially as a bulking agent) and avoids negative physiological effects is highly desirable.
It has now been found, that carbohydrates in the 5-C-hydroxymethyl-hexose series can be effectively used as replacements for sugar, especially in baked goods. These carbohydrate derivatives provide sucrose-like functionality (i.e., bulk, texture and stability) with significantly reduced calories compared with sucrose. In addition, many of these carbohydrate derivatives are easier to synthesize than currently available functional sugar substitutes. It is believed that they are essentially free of the significant negative physiological effects (i.e., flatus and diarrhea) generally associated with such compounds. It has also been shown that saccharides containing a 5-C-hydroxymethyl-hexose component provide similar benefits. This also holds true for the alditols of these carbohydrates (e.g., 5-C-hydroxymethyl-hexitols, 5-C-hydroxymethyl-aldohexosyl polyol derivatives, alkyl derivatives (e.g., 5-C-hydroxymethyl-aldohexosyl glycerol and 5-C-hydroxymethyl-aldohexosyl-glucitol) of the carbohydrates (i.e., alkyl 5-C-hydroxymethyl-aldohexosides), and 1,6-anhydro-.beta.-L-, and 1,6-anhydro-.beta.-D derivatives of the pyranose compounds (i.e., the bicyclic tautomeric forms) and the related derivatives of the ketohexoses.